1. Field of the Invention
The present invention relates to a control device for an internal combustion engine.
2. Description of the Related Art
Japanese Unexamined Patent Publication No. 2-169834 discloses an internal combustion engine having a spark plug and a fuel injector for injecting fuel directly into the cylinder, the fuel injector injecting a part of an amount of fuel to be injected, during an intake stroke, and injecting a remaining part of the amount of fuel to be injected, during a compression stroke.
In this engine, however, when a fuel injection during the intake stroke, a fuel injection during the compression stroke, and an ignition are carried out in one combustion cycle on the basis of an engine control value, for example, an amount of fuel to be injected during the intake stroke, an amount of fuel to be injected during the compression stroke, and an ignition timing which are calculated on the basis of different engine running states detected at different points in time, a problems arises in that a good ignition and a good combustion cannot be obtained, as described below.
Referring to FIG. 7, for example, at No. 1 cylinder, when the engine load of the engine running state V.sub.1 at T.sub.10 immediately before the fuel injection during the intake stroke in the No. 1 cylinder is a high engine load, in which an entire amount of fuel to be injected is injected during the intake stroke, a fuel injection during the intake stroke is carried out on the basis of the fuel injection time and the fuel injection timing calculated on the basis of the engine running state V.sub.1, and the entire amount of fuel to be injected is injected during the intake stroke in the No. 1 cylinder. Then, at T.sub.11 immediately before the fuel injection during the compression stroke in the No. 1 cylinder when the engine load of the engine running state V.sub.2 is a middle engine load, in which a part of the amount of fuel to be injected is injected during the intake stroke and a remaining part of the amount of fuel to be injected is injected during the compression stroke, a fuel injection during the compression stroke is carried out on the basis of the fuel injection time and the fuel injection timing calculated on the basis of the engine running state V.sub.2.
Namely, during one combustion cycle of the engine, the entire amount of fuel calculated on the basis of the engine running state V.sub.1 at T.sub.10 is injected during the intake stroke and a part of the amount of fuel calculated on the basis of the engine running state V.sub.2 at T.sub.11 is injected during the compression stroke. Therefore, since the amount of fuel injected during the one combustion cycle becomes much larger than an ideal amount of fuel to be injected, and thus an air-fuel mixture becomes overrich, a problem arises in that a good ignition and a good combustion cannot be obtained. As a result, a large amount of smoke is produced, a misfire occurs, and the engine torque is fluctuated. Also, since the ignition timing is far different from an ideal ignition timing, the ignition and the combustion is further deteriorated.